The invention discloses a 
laser coaxial 
powder feeding composite manufacturing 
machine tool which comprises a cradle type 
workbench, a spindle, a material additive manufacturing mechanism, a material reducing 
machining mechanism and an online defect detection mechanism. The material additive manufacturing mechanism comprises a 
nozzle and a 
powder feeding device connected with the 
nozzle. A 
laser head is arranged at the position of the 
nozzle and connected with a 
laser generator. The material additive manufacturing mechanism is clamped by a nozzle bracket. The material reducing 
machining mechanism comprises a tool, a tool 
magazine and a tool changing bracket. The online defect detection mechanism comprises a defect detection head and a detection 
signal collection and analysis 
system. The invention further discloses a workpiece composite manufacturing method. The process of the workpiece composite manufacturing method mainly comprises the steps that material additive manufacturing, online defect detection and material reducing 
machining are carried out cyclically, and finally composite manufacturing is completed. By means of compounding of material additive manufacturing, material reducing machining and online defect detection, one-time forming of workpieces high in size precision and surface quality and low in internal defect is guaranteed, the production period is effectively shortened, and the part 
manufacturing quality and precision are guaranteed.